Elevator cars have doors which enclose the interior of the car when the car travels along a hoistway. The doors, which translate across an opening, are supported at their upper periphery by rollers hung from a car lintel, and at their lower periphery by gibs guided by grooves within a car doorsill. When the doors close, there are some openings around the door edges.
Typically, the area of the openings can be minimized by using heavier gauge material and/or by requiring tighter manufacturing tolerances. However, heavier gauge material is more expensive and tighter tolerances may cause installation problems. Normal practice requires relatively looser tolerances to allow for manufacturing variations. As a result, the openings, which are larger than desirable, allow noise to migrate to the interior of the car.
Further, there is a certain amount of backlash between the lintel and the rollers and between the gibs and the doorsill. The backlash may allow the car doors to rattle as the car encounters aerodynamically induced vibration loads during car travel thereby increasing noise and vibration within the interior of the car.